Purpose: This study was to analyze refractive error and corneal curvature radius in childhood myopia.
Methods: The average age of 9.92 ± 1.08 years Children 50 people(24 males and 26 females) were evaluated for refractive error with an automatic refractometer, Pentacam was used to measure the corneal curvature radius.
Results: The mean total spherical diopter was -2.43 ± 1.39D and astigmatism diopter was -0.75 ± 0.66D, horizontal radius of curvature was 7.88 ± 0.23mm, vertical radius of curvature was 7.67 ± 0.23mm, corneal astigmatism -1.18 ± 0.56D, diameter was 11.75 ± 0.47mm, eccentricity was 0.55 ± 0.10. There was no significant difference spherical diopter(t=-0.357, p=0.722), corneal astigmatism (t=1.410, p=0.162), eccentricity(t=0.627, p=0.532) in male and female, astigmatic diopter(t=2.097, p=0.039), horizontal radius of curvature(t=2.397, p=0.018), vertical radius of curvature(t=2.685, p=0.009), diameter(t=2.157, p=0.033) were significantly different. There was no significant difference spherical diopter(t=-0.952, p=0.343), astigmatism diopter(t=1.260, p=0.211), horizontal radius of curvature (t=-0.596, p=0.553) vertical radius of curvature(t=-0.495, p=0.621), corneal astigmatism(t=0.662, p=0.509), diameter (t=-0.411, p=0.682), eccentricity (t=0.080, p=0.937) between in male and female.
Conclusions: Male and female were significant different astigmatism diopter, horizontal radius of curvature, vertical radius of curvature, diameter in childhood myopia. There was no significant difference between right eye and left eye.
To evaluate the possibility of negative reaction at seismic isolation bearings subject to seismic load, seismic records of El-Centro and artificial earthquake wave were applied to a single-plate girder bridge with various analytical parameters of curvature radii and skew angles. It is found that seismic analysis using those parameters should be carried out to prevent negative reaction at support.
Curved girders show very complex behavior compare to straight girders because the torsional moments always act on the structure even if there are no additional loads except self-weight. For this reason, engineers need to consider torsional behavior when design or analyse structure. However, most of curved bridges are designed as a series of straight girders because design specification does not reflect the curved beam theory. In this paper, curved girders are analysed by FEA program and the results are compared with the results of straight girders. Selecting the radius of curvature as a parameter, suitable analysis method for design of horizontally curved girder was suggested.